1,mux/muy=px/py=2/3=x/y,x=(2/3)y,带入PxX+PyY=240,Px=2元，Py=3元.求出X Y.
2,货币的边际效用=MUx/Px=X/2.X已经在第一问求出。将X Y带入效用函数，可以求出总效用。

3，收入的增加量=（PX2-PX1)X.X已经在第一问求出，PX2=2(1+0.44).

楼上的货币编辑效用带入错了吧？MUm=MUx/Px=Y/2=.
总效用函数也应该可以TU=MUm×m（预算）来计算吧？

  if utility function is U=xy, then the Marshal demand functions are x=m/2Px, y=m/2Py, the indirect utility function is V(p1,p2;m)=m^2/4PxPy, lamda=dV/dm=m/2PxPy.
hence:
(1) X=240/4=60,y=240/6=40, u*=2400
(2)marginal utility of money =lamda=240/(2*2*3)=20
(3)you must know the Hicks demand functions, which are solved from the problem:
  Min e=xP1+yP2 s.t. U=xy=u=2400
the decision functions are hicks demand functions:
x=h1(p1,p2,u)=sqrt(u*P2/P1),
y=h2(p1,p2,u)=sqrt(u*p1/p2)
the value function, or the expenditure function is
e(p1,p2,u)=2sqrt(p1*p2*u)=2sqrt(2*1.44*3*2400)=288

科师的吧，知名不具啊。
(1)X=60,Y=40;
(2)λ=20,U=2400;
(3)ΔI=48。I增加20%。

知名不具？